The present invention relates to an antenna-integrated radio communication device, transmitter and receiver provided with an antenna function to be used for microwave communications.
Recently, in accordance with improvements in the processing speed of information processing apparatuses, developments in resolution of image processing apparatuses and so on, attention has been paid to high-speed large-capacity personal communications at high frequencies of microwaves and the like. Particularly, in the milliwave band, power loss in the connection portions of an antenna and a high-frequency circuit becomes increased, and therefore, it is attempted to develop an antenna-integrated radio communication device in which an antenna is integrated with a high-frequency circuit.
As an antenna-integrated radio communication device, there is the one disclosed in Japanese Patent Laid-Open Publication No. HEI 9-237867. As shown in FIG. 8, this antenna-integrated radio communication device includes an antenna circuit substrate A in which an antenna element 3 and a high-frequency line 4 for feeding the antenna element 3 are formed on a first dielectric substrate 2 and a high-frequency device circuit substrate B in which a high-frequency device 9 is housed in a cavity 8 formed in a part of a second dielectric substrate 7 and sealed with a lid member 10 and a transmission line 11 for transmitting a signal to the high-frequency device 9 is formed. The antenna circuit substrate A and the device circuit substrate B are laminated and integrated with each other, and the high-frequency line 4 of the antenna circuit substrate A and the transmission line 11 of the high-frequency device circuit substrate B are electromagnetically coupled and connected with each other via a slot 6.
Moreover, as another antenna-integrated radio communication device, there is the one described in Japanese Patent Laid-Open Publication No. HEI 8-250913. As shown in FIG. 9, this antenna-integrated radio communication device includes a base 41 constructed of upper and lower dielectric layers 41a and 41b and a ground layer 41c placed between the dielectric layers 41a and 41b, and the ground layer 41c is provided with a slot portion 41d. Moreover, a flat antenna 41e is formed on the lower surface of a package 3 that seals and houses a semiconductor integrated circuit, and a microstrip line 91 for feeding is formed on the package inner surface side of the upper dielectric layer 41a. Then, this microstrip line 91 is electrically connected to an output terminal 2a and an input terminal 93 of an MMIC (Monolithic Microwave Integrated Circuit) 92 with bonding wires 2b and 94.
In the antenna-integrated radio communication device shown in FIG. 8, ground layers 5 and 12 exist above and below the high-frequency line 4 that feeds the antenna element 3. Therefore, the upper and lower ground layers 5 and 12 do not become equipotential particularly at very high frequencies as in the milliwave band, and electric power is converted into unnecessary electromagnetic waves in a parallel plate mode to propagate between the upper and lower ground layers 5 and 12, loosing the electric power from substrate end surfaces. As a method for restraining this unnecessary mode, there can be considered a method for equalizing the potentials of the two ground layers by connecting the upper and lower ground layers via a lot of through holes. However, inductance of the through holes becomes unignorable as the frequency becomes higher, and therefore, this method has a limitation. As a result of the generation of electromagnetic waves in the unnecessary mode described above, there is a problem that the efficiency of the antenna element 3 is reduced. Moreover, if substrate materials of different material properties are laminated in the antenna-integrated radio communication device, there is a problem that the semiconductor chip mounting reliability is degraded due to the manufacturing problems such as lamination displacement and exfoliation and the warp of the substrates because of differences in the thermal expansion coefficient between them.
Moreover, in the antenna-integrated radio communication device shown in FIG. 9, in order to form an array of flat antennas 41e, it is required to branch the feeding microstrip line 91 to feed each flat antenna 41e and house the feeding microstrip line 91 in the same package as that of the MMIC 92. However, unnecessary electromagnetic waves radiated from the feeding microstrip line 91 and the MMIC 92 exert adverse influences on them, possibly causing not only a reduction in efficiency but also malfunction.
As described above, it has been difficult for the conventional antenna-integrated radio communication devices shown in FIG. 8 and FIG. 9 to concurrently satisfy the antenna efficiency, the directivity of the formed array and the semiconductor chip mounting reliability.
Accordingly, the object of the present invention is to provide an antenna-integrated radio communication device capable of improving the efficiency and directivity of the antenna, improving the semiconductor chip mounting reliability with restrained warp of the substrate and preventing the malfunctioning of the high-frequency circuit as well as a transmitter and a receiver employing the communication device.
In order to achieve the aforementioned object, the present invention provides an antenna-integrated radio communication device having a dielectric multilayer substrate in which a plurality of dielectric layers are laminated and a high-frequency circuit on which semiconductor chips are mounted, wherein
a plurality of conductor patches, an antenna feeder line for feeding the plurality of conductor patches, one ground layer and the high-frequency circuit connected to the antenna feeder line are separately arranged on an upper surface, between layers and on a lower surface, respectively, of the dielectric multilayer substrate, and the one ground layer is arranged between an antenna section comprised of the plurality of conductor patches and the antenna feeder line and the high-frequency circuit.
According to the antenna-integrated radio communication device of the above-mentioned construction, the plurality of conductor patches, the antenna feeder line, the ground layer and the high-frequency circuit are separately arranged on the upper surface, between the layers and on the lower surface, respectively, of the dielectric multilayer substrate, and the ground layer is arranged between the antenna section constructed of the plurality of conductor patches and the antenna feeder line, and the high-frequency circuit. With this arrangement, the antenna section and the high-frequency circuit are spatially separated from each other by the ground layer, and therefore, the mutual adverse influences of the antenna circuit and the high-frequency circuit can be eliminated. Moreover, the ground layer is only one layer, and therefore, the antenna feeder line becomes able to perform the transmission in the desired quasi-TEM mode even at a high frequency in the milliwave band. Therefore, the efficiency and directivity of the antenna can be improved, and the high-frequency circuit can be prevented from malfunctioning. Furthermore, the plurality of conductor patches and the antenna feeder line are formed in different layers, and therefore, the efficiency of the antenna and the characteristics of the antenna feeder line can be independently optimized.
Moreover, in one embodiment, the dielectric multilayer substrate is a dielectric multilayer substrate comprised of a first dielectric layer, a second dielectric layer and a third dielectric layer,
the plurality of conductor patches are arranged on an upper surface of the first dielectric layer of the dielectric multilayer substrate,
the antenna feeder line is arranged between the first dielectric layer and the second dielectric layer,
the ground layer is arranged between the second dielectric layer and the third dielectric layer,
the high-frequency circuit is arranged on a lower surface of the third dielectric layer of the dielectric multilayer substrate, and
the antenna feeder line is electromagnetically coupled with the high-frequency circuit via a slot hole provided for the ground layer.
According to the antenna-integrated radio communication device of the above-mentioned embodiment, the dielectric multilayer substrate has the plurality of conductor patches provided on its upper surface, the antenna feeder line provided between the first and second dielectric layers, the ground layer provided between the second and third dielectric layers and the high-frequency circuit provided on the lower surface, and the antenna feeder line is electromagnetically coupled with the high-frequency circuit via the slot hole provided for the ground layer. This allows the obtainment of an optimum structure capable of easily improving the efficiency and directivity of the antenna and preventing the high-frequency circuit from malfunctioning.
Moreover, in one embodiment, the plurality of conductor patches are arranged in an array form,
the antenna feeder line is branched into a plurality of lines, and the plurality of conductor patches and end portions of the branches of the antenna feeder line overlap each other.
According to the above-mentioned embodiment, the directivity of the antenna can be efficiently improved with the plurality of conductor patches arranged in an array form and the end portions of the branches of the antenna feeder line overlapping the patches.
Moreover, in one embodiment, a distance in a lengthwise direction of the antenna feeder line in a region where the plurality of conductor patches and the end portions of the branches of the antenna feeder line overlap each other is approximately a quarter of an effective wavelength of a prescribed electromagnetic wave.
According to the antenna-integrated radio communication device of the above-mentioned embodiment, the distance in the lengthwise direction of the antenna feeder line in the region where the plurality of conductor patches and the end portions of the branches of the antenna feeder line overlap each other is approximately a quarter of the effective wavelength of the prescribed electromagnetic wave. With this structure, loss due to reflections on the end portions of the antenna feeder line can be reduced, enabling the efficient feeding of each conductor patch from the antenna feeder line.
Moreover, in one embodiment, the dielectric layers of the dielectric multilayer substrate are formed by integrally baking a ceramic material that has a relative dielectric constant of 4 to 10.
According to the above-mentioned embodiment, by forming the dielectric layer of the dielectric multilayer substrate by the integral baking of the ceramic material that has a relative dielectric constant of 4 to 10, the structure of the dielectric multilayer substrate can be accurately provided. Moreover, strong substrate strength can be obtained by the use of the ceramic material, and the warp of the substrate is restrained, allowing the semiconductor chip mounting reliability to be improved.
Moreover, this invention provides an antenna-integrated radio communication device, wherein a plurality of conductor patches, an antenna feeder line, a ground layer and a high-frequency circuit are provided in order from an upper surface to a lower surface of the dielectric multilayer substrate on the upper surface, between layers and on the lower surface, respectively, of the dielectric multilayer substrate in which three dielectric layers are laminated.
According to the antenna-integrated radio communication device of the above-mentioned construction, the antenna section constructed of the plurality of conductor patches and the antenna feeder line, and the high-frequency circuit are spatially separated from each other by the ground layer, and therefore, the mutual adverse influences of the antenna section and the high-frequency circuit can be eliminated. Moreover, the ground layer is only one layer, and therefore, the antenna feeder line can perform transmission in the desired quasi-TEM mode even at a high frequency in the milliwave band. Therefore, the efficiency and directivity of the antenna can be improved, and the high-frequency circuit can be prevented from malfunctioning. Furthermore, the plurality of conductor patches and the antenna feeder line are formed on different layers, and therefore, the efficiency of the antenna and the characteristics of the antenna feeder line can be independently optimized.
Moreover, in one embodiment, each dielectric layer of the dielectric multilayer substrate has a thickness of 100 microns to 200 microns.
According to the above-mentioned embodiment, by making each dielectric layer of the dielectric multilayer substrate have a thickness of not greater than 200 microns, it is enabled to perform transmission in the desired quasi-TEM mode between the microstrip line used for the antenna feeder line and the ground layer at a frequency of, for example, 60 GHz when the dielectric layer has a relative dielectric constant of 4 to 10. If the thickness of each dielectric layer exceeds 200 microns, then the transmission loss of the microstrip line used for the antenna feeder line is increased. When the thickness of each dielectric layer is not greater than 100 microns, the interval between the conductor patch and the ground layer becomes narrow, and this reduces the antenna radiation efficiency and reduces the strength of the dielectric multilayer substrate.
Moreover, this invention provides a transmitter and a receiver employing the above antenna-integrated radio communication device.
According to the transmitter and the receiver of the above-mentioned construction, the transmitter and the receiver can be downsized. Moreover, by virtue of the formation of the antenna section and the high-frequency circuit on the upper and lower surfaces, respectively, of the dielectric substrate, signal loss between the antenna section and the high-frequency circuit can be reduced, and the communication distance can be increased without increasing the consumption power.